Joule Thief

[dasimpson]

cool i think 3 amp might be to much my batterys have a trickle charge of 250ma but with how little sun we have that 3 amp might be good
looks like they might of stopped selling them bugger oh well i was just thinking if i got a 5 or 6v solar panle to charge 3 batterys but only pull power from one for the joule thief or maybe put an led on the posertive to drop the voltage

[Pirate88179]

Dasimpson:

I am sorry, I made an error.  Those cells were .5 volts @ 1 amp, not the 1.5 volts I had stated.  So, I have them hooked up to give me 1.5 volts @ 1 amp.

I am sorry for the mistake, it was late when I was typing that.

Bill

[dasimpson]

ah no problem m8 i know the exact ones you mean

[jeanna]

I am finding something interesting about the jtc as I experiment with lasersaber's air batteries.

I have a couple of these that put out about 30mA
So, this should be enough to run a jtc with a secondary, and indeed it is.
BUT I cannot get anything like the high voltage spikes from this galvanic pile battery that I do from a chemical AAA.

So, I am wondering what this means about the joule thief and how it works.

I am beginning to think that the jtc is "asking for" a high amps or high charge for a very short time with each pulse. If that high charge is not available, the secondary output is lower.

If this is so, then a higher frequency jtc should drain a battery faster than a lower frequency jtc, which it does NOT.
The smaller transistors are on jtc's that have higher frequency and they last for at least 10 hours.

The dmm does not show any of this, of course because it is too fast to read, but this might explain why a 2500mAH NiMH will only last 5 to 6 hours when the dmm says it is drawing 100mA. It SHOULD be able to last at least 12 hours but it does not. If I use the rheostat at the battery where lidmotor added one, which is at the pos of the battery,  the battery life improves.

I checked this out using my scope, on a few high power circuits I have and the highest I could get using the air battery was 28v where it was over 450 with a AAA. I even put a few in series to see if the higher input voltage would help, and it seemed that this made very little difference!

It is very curious but I am glad that at least something is addressing the curiously lower than predicted life of the battery which runs the jtc.

thank you,

jeanna

[WilbyInebriated]

I am beginning to think that the jtc is "asking for" a high amps or high charge for a very short time with each pulse. If that high charge is not available, the secondary output is lower.

indeed it is 'asking for'. the 'dead' AA battery is 'dead' in respect to its voltage 'capacity', 1v instead of 1.5-6v but still contains a large 'capacity' of amperage, relatively speaking of course. the jt uses this amperage to saturate the ferrite core which then effects the switch and it starts all over. your galvanic pile doesn't have this 'capacity' of amperage that the AA does... grossly simplified, sorry.